1. Technical Field of the Invention
The present invention relates to an optical disc apparatus and more particularly to a control technique of recording power at the time of data recording.
2. Description of the Related Art
In DVD recording with a conventional optical disc apparatus, in order to control laser output at the time of data recording, the optical disc apparatus performs the steps of: periodically suspending recording operation; measuring and calculating a β value of a signal recorded immediately before suspending the recording operation from a reproduced signal; comparing measurement and calculation results with a target β value prestored in the apparatus; and controlling the laser power so as to zero the difference therebetween to perform recording power correction control (referred to as Walking OPC (optimum power control)). However, the β value is not directly connected with recording quality, and the relation between the β value and the recording quality differs depending on performance variations among apparatuses, disc radial positions of an optical disc, etc. Therefore, even if the recording power is corrected so as to meet the prestored target β value, the recording quality, for example jitter, is not necessarily improved.
Further, in order to improve the recording quality of optical disc apparatuses, a technique for correcting recording parameters by use of the Time Interval Analyzer function (referred to as the TIA function) for measuring a phase error between a reproduced signal from which recording marks are read and a reference signal has been studied in recent years. Correction techniques by use of the TIA function are disclosed, for example, in JP-A-2006-302332, JP-A-2007-48412, and JP-A-2007-18582. JP-A-2006-302332 discloses a technique for preventing recording deterioration if an environmental condition such as temperature changes during data recording with a recording/reproducing apparatus. The technique includes the steps of: seeking a recordable zone on a recording medium; tentatively recording only recording parameters of a shortest recording mark by use of particular patterns with several added patterns of correction values; reproducing the patterns; and correcting the recording parameters based on the amount of edge shift of the recording mark. JP-A-2007-48412 discloses a technique for trial record processing onto a data recording medium with a data recording apparatus. The technique adjusts a parameter for changing the rising position of a first pulse of a recording strategy, a parameter for changing the rising position of a cooling pulse, and a parameter for changing the rising position of a last pulse. JP-A-2007-18582 discloses a technique for enabling the setup of a write strategy (recording strategy) with high accuracy in a short time even at the time of high-speed recording with an optical data recording apparatus. The technique includes the steps of: tentatively recording data including a plurality of types of marks onto an optical recording medium according to a predetermined write strategy; detecting a gap between edge timing and a clock for each edge of each mark whose value changes in a reproduced signal of the recorded data; and correcting the write strategy for each mark so that all gaps coincide with each other.